From 8ff441c6ff42252d1292ea8989d86106563c6c18 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Mon, 21 Sep 2020 11:41:13 +0300
Subject: [PATCH] Support audio effects

---
 libs/audio/CMakeLists.txt    |  2 +-
 libs/audio/source/engine.cpp | 24 +++++++++++++++++++-----
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/libs/audio/CMakeLists.txt b/libs/audio/CMakeLists.txt
index 3689f27f..cdca7459 100644
--- a/libs/audio/CMakeLists.txt
+++ b/libs/audio/CMakeLists.txt
@@ -5,4 +5,4 @@ file(GLOB_RECURSE PSEMEK_AUDIO_SOURCES RELATIVE "${CMAKE_CURRENT_SOURCE_DIR}" "s
 
 add_library(psemek-audio ${PSEMEK_AUDIO_HEADERS} ${PSEMEK_AUDIO_SOURCES})
 target_include_directories(psemek-audio PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/include")
-target_link_libraries(psemek-audio PUBLIC psemek-sdl2 psemek-log psemek-util SDL2_mixer)
+target_link_libraries(psemek-audio PUBLIC psemek-sdl2 psemek-log SDL2_mixer)
diff --git a/libs/audio/source/engine.cpp b/libs/audio/source/engine.cpp
index 5c1579b4..b1258ffb 100644
--- a/libs/audio/source/engine.cpp
+++ b/libs/audio/source/engine.cpp
@@ -1,8 +1,6 @@
 #include <psemek/audio/engine.hpp>
 #include <psemek/sdl2/init.hpp>
 #include <psemek/log/log.hpp>
-#include <psemek/util/not_implemented.hpp>
-#include <psemek/util/unused.hpp>
 
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_mixer.h>
@@ -71,6 +69,8 @@ namespace psemek::audio
 			std::shared_ptr<sample_impl> sample;
 			bool loop;
 
+			std::vector<std::shared_ptr<effect>> effects;
+
 			stream_impl(int channel, std::shared_ptr<sample_impl> sample, bool loop)
 				: channel(channel)
 				, sample(sample)
@@ -85,13 +85,27 @@ namespace psemek::audio
 
 			void push_effect(std::shared_ptr<effect> e) override
 			{
-				unused(e);
-				util::not_implemented();
+				effects.push_back(e);
+				Mix_RegisterEffect(channel, &effect_func, nullptr, e.get());
 			}
 
 			void clear_effects() override
 			{
-				util::not_implemented();
+				effects.clear();
+				Mix_UnregisterAllEffects(channel);
+			}
+
+			static void effect_func(int, void * data, int len, void * udata)
+			{
+				auto e = reinterpret_cast<effect *>(udata);
+
+				if ((len % 2) != 0)
+				{
+					log::error() << "Cannot apply " << e->name() << " effect: number of bytes not even";
+					return;
+				}
+
+				(*e)(reinterpret_cast<std::int16_t *>(data), len / 2);
 			}
 
 			void start() override